Testing system for telephone-lines.



PA ENTED EEG." 18, 1906. w; w. DEAN. TESTING SYSTEM FOR TELEPHONE LINES.

. APPLICATION FILED JUNEZQ, 1903.

UNITED STATES PATENT OFFICE.

WILLIAM WV. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCHBOARD & SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A

- CORPORATION OF ILLINOIS.

TESTING SYSTEM FOR TELEPHONE-LINES.

Specification of Letters Patent. I

Patented Dec. 18, 1906.

To all whom it may concern.-

Be it known that 1, WILLIAM W. DEAN, a citizen of the United States of America, and a resident of Chicago, county of Cook, and. State of Illinois, have invented a new and useful Improvement in Testing Systems for Telephone-Lines, of which the following is a specification.

My invention relates to improvements in means for connecting the common portion of a busy testing-circuit to the testing-strand of an operators connective means when it is desired to use the same for testing.

I accomplish the desired end in this invention by providing a plug-seat switch for a plug of the connecting means and include the normally open contacts of said switch in the testing-conductor, whereby when the plug is out of its seat the testing-circuit is completed at that point and a test may be made. The testing-plug is preferably so provided with the seat whereby when lifted therefrom the circuit is completed and the said plug may be used for testing.

My invention is illustrated in the accompanying drawing, in which the figure is a diagram of a telephone system including subscribers lines terminating at different central offices and operators connective means to establish connections at one of said ofiices, as well as between the lines terminating at the different ofiices.

L indicates a telephone-line extending in two limbs 2 and 3 from the substation to the central office C, where it is fitted, as is usual, with a line-si nal S, an answering-jack J, and a plurality of multiple acks, such as J 2 and J At the substation a bell 4 and a com denser 5 are included in a permanent bridge of the telephone-line, while a transmitter 6 and a receiver 7 are included in a second bridge that is normally open at the switchhook 8. A cut-off relay R? is legged to ground from the sleeve side of the jack-section of the telephone-line and serves to render the line-signal inoperative when a connection is established with the line. The line conductor 3 is normally connected by a common lead 9, including the line-relay R, which controls the local circuit of the line-signal S with the live pole of a central common battery B. The operators cord-circuits each includes an answering-plug P and a callingplug P having tip and sleeve contacts adapted to register with the corresponding contacts of the jacks of the lines. The tipcontacts of said plugs are connected together by flexible strands t and i and the interposed condenser 0, while their sleeve-contacts are joined by the strands s and s and the inter posed condenser 0 Supervisory relays r and r are connected upon opposite sides of the battery B across the answering end of the cord-circuit and together control the local circuit of the supervisory signal S while similar supervisory relays r and r are connected upon opposite sides of a similar common battery B across the calling end of the cord-circuit, said relays controlling the local circuit of the supervisory signal S associated with the calling-plug of the cord-circuit.

Tip-strand t of the cord-circuit is normally open, and the forward portion thereof is connected by spring 10 of supervisory relay r with the conductor 11, leading to a normally open contact of the plug-seat switch in which the calling-plug P normally rests. From this switch the conductor 12 extends to the high-resistance and high-impedance test-relay 1' whose opposite terminal is grounded. This relay controls, through its normally open contacts, a path for current from the battery 13 over conductor 9 and conductor 13, including the tertiary Winding of the operators inductioncoil.

The operators telephone set, including a receiver 17, the secondary of her inductioncoil, and a condenser 0 is adapted to be bridged across the calling end of the cord-circuit by springs 18 of a suitable listening-key. A ringing-generator 19 is adapted to be connected with the forward portion of the strands t of the cord-circuit by means of tip-ringing key-spring 20, while the forward portion of the sleeve-strand is simultaneously connected, through spring 20 of said key, with con ductors 21 and 9, the former including a suitable resistance 22. The apparatus so far described is used for completing connections between subscribers terminating at the exchange C. I have shown another line L of the same type as L, terminating at the branch oflice C and a trunk-line L extending between said o'llices. This trunk-line is provided with jacks J J J &c., in any number at the oflice C and with a grounded retardaground from the strand t tion-coil 23 from the sleeve side of the trunk. This trunk-line extends in two limbs 24 and 25 to the oflice C where the said limbs are connected together through the windings 26 and 27 of a repeating-coil V and a'high-resistance trunk-relay T The other windings 28 and 29 of said repeating-coil, together with the condenser 0 serve to connect the tip and sleeve strands t and s of the trunkeord, which at their opposite ends are connected, respectively, with the corresponding contacts of the trunk-plug P adapted to be inserted in any one of the jacks of the called telephone-lines. A short circuit of said high resistance trunk-relay 1, consisting of conductors 30 and 31, is controlled by normally open contacts of the tip-relay r legged to A third relay 1* is associated with the trunk and is connected upon one side with the strand 8 by conductor 32, while upon the other side it is connected by conductors 33 and 34 with the live pole of the common battery B A disconnect-signal S and a ringing-signal S are provided for this end of the trLmk-circuit and are suitably controlled by means of said relays, together with the locking-relay 1 The spring 35 of said relay 1" is connected with the forward portion of the strand t of the trunk-cord and normally engages with a contact connected with conductor 36, leading to a plug-seat switch in which the trunkplug P normally rests. This switch is connected by conductor 37 with one pole of the highresistance and high-impedance testre lay r, associated with the trunk-circuit. The operators telephone 38 is connected, by meansof an order-circuit 39, with the orderkey 40 belonging to the operator at the ex change 0.

In the operation of the system the sub scriber A, for example, takes up his receiver, thereby completing a path for current from the battery B over the telephone-line and operating his signal S. Upon observing the signal the operator inserts the answeringlug P of her cord-circuit in one of the acks of the line and connects her instrument therewith to receive the order of the subscriber. The insertion of the plug P closes a path for current from the battery B over the j ack-section of the telephone-line to operate the cutoff relay R and thence over the line conductors 2 and 3 of the telephone-line, thereby operating both supervisory relays r and T the former serving to open the circuit of the supervisory signal S to prevent its lighting. If the connection desired is with a subscriber whose line terminates at the same office, the line is tested, by means of the calling-plug P of the cord-circuit, in the usual manner. The current will flow from the test-Ting of the wanted line, if the line is busy, over the tip-strand t of the cord-circuit, the tip-spring 10 of the relay 1", conductor 11, plug-seat-switch contacts, since the plug is now out of the same and the said contacts are closed, and conductor 1.2 to and through the test-relay r to ground. This relay is therefore operated and causes a click in the operators telephone. Said test-relay is separated from the cord-circuit and from all of the cord-circuits at the operators position to which it belongs, and is therefore not afiected by short circuits in any of said cordcircuits or by leakage upon some or all of them. If the line is found idle, the calling plug P is inserted in the telephone-line and the ringing generator 19 operated in the usual way, the cut-off relay of the called line being maintained operated by current from the battery B through conductors 21 and 9*. Upon the insertion of the calling-plug P the supervisory relay 1' is actuated to cut out the test-relay r whereby it is not again connected with the cord-circuit during the connection, and the operators telephone may be connected at any time with the said cordcircuit without severing the cordcircuit strands or without connecting the test-relay therewith. Assuming that the subscriber wanted is located at the exchange C the operator at exchange C is informed over the order circuit that connection is desired with the wanted line. This operator, who may be termed the B operator, informs the first or A operator What trunk to use for the connection. The A operator inserts the plug P in the jack of that trunkline, while the B operator inserts the plug P of the trunk into the jack of the wanted line after having properly tested the same to determine its idle or busy condition. The insertion of the plug P into one of the jacks of the trunk completes a path for current through the retardation-coil 23 over the sleeve-strand s of the cord-circuit and operates the supervisory relay r, thereby permitting current to flow over the metallic telephone-line and through the high-resistance trunk-relay r at the incoming end of the trunk. This relay is of such high resistance that the tip supervisory relay r is unable to actuate, so that the supervisory signal S is now lighted. In order to test the line L the trunk-operator makes use of the plugs P in the usual manner, the test-relay 1" being now connected with the strand i of said cord through contacts of the plug-seat switch. When the plug is in its seat, the said test-relay is isolated or disconnected from the trunkcords. It will be understood that each such test-relay is common to the trunks for each operator.

actuating the cut-ofi relay R of the-line L The relay 9" is likewise operated and serves, by means of the spring 35, to disconnect the conductor 36 of the test-relay and to com- The insertion of the plug P closes the path for current from battery B over the sleeve-strand s of the cord-circuit, thereby plete the tip-strand t for conversation. Its spring 41 also engages its front contact, and the path for current from the battery B over conductors 34 42, spring 41, conductor43, point 45, conductor 46, including ringinglamp S and normal contacts of the lockingrelay 1 is completed. This signal is therefore lighted to indicate that the subscriber has been called, but has not yet responded, the ringing-generator 47 being provided to call the subscriber in the same manner as has been described with reference to the cord circuit and the cuto'lf relay being held up during r nging also in the same manner. Upon the response of the subscriber D a path for current is completed over the metallic telephone-line and the strand t of the cord circuit and thence through the relay W, a spring of this relay serving to close the short circuit of high resistance trunk relay r whereby a sufficient flow of current is permitted over the trunk-line to actuate the su pervisory relay r in the cord-circuit at the central oi'lice C. The supervisory signal S is thus extinguished to indicate the response of the called subscriber to the A operator. The operation of relay 1' also causes its grounded spring 48 to engage its front contact, which is connected with conductor 49, leading to the oint 45 and containing the winding of the ocking-relay 1". This relay is therefore connected with the live pole of the battery B and is operated to 0 en the circuit of the ringing-lamp S and to a. so complete a locking-circuit for itself through conductor 50 and its front contacts. Thus the locking-relay prevents a second operation of the ringing-lamp during the connection or until the sleeve1'elay r is deenergized. At the termination of the conversation when the subscriber D returns his receiver to its hook the tip-relay r is deenergized, thereby opening the short circuit about the relay 1, which is again thrown into the circuit of the outgoing end of the trunk and causes the tip supervisory relay 7' to be deenergized and close its normal contacts, thereby lighting supervisory lamp S The supervisory lamp S is lighted by the hanging up of the calling subscribers telephone in the usual manner. The operator at the A oflice seeing both signals takes down the connection. By so doing the relay 7 is again deprived of operating-current, so that its normal contacts are closed, and a path for current is now completed through disconnect-lamp 3*, said path being traced from the live pole of the battery 13, over conductors 34 and 42, spring 41 of relay 1*, conductor 43, point 45, conductor 51, containing lamp 8*, the normal contacts of the trunk-relay 1' conductor 52, and the normal contacts of the relay r This lamp is therefore lighted to indicate to the B operator that the conversation has terminated and disconnection has been made at the outgoing end of the trunk. She therefore withdraws the trunk-plug P and returns it to its seat. It will be observed that the lamp S acts as a guard-signal in case connection is established with the wrong outgoing trunk, since the relay 7 is alone actuated under such conditions, and completes a path for current through the lamp S, including conductors 34 and 53, the front contacts of said relay 1, conductor 51, including the lamp, point 45, conductor 43, spring 41 of relay 7", its normal contact, and grounded conductor 54. Thus the operator at station 0 is notified that an error has been made, and the A operator is notified. Under normal conditions therefore the test-relay associated with the trunk, as well as that associated with the cord-circuit, is disconnected and wholly isolated. This plug-seat arrangement is of special advantage in connection with the trunk-circuit, since the trunk-operators are. not ordinarily provided with listening-keys.

Having described my invention, what I claim is r 1. In a telephone system, the combination with telephone-lines, of operators connecting cords and plugs, a plug-seat switch for each plug, a supervisory relay associated with each cord, a testing-conductor common to the cords, said testing-conductor being connected with the cords through contacts of the associated plug-seat switch and disconnected therefrom through the contacts of said relay, substantially as described.

2. In a telephone system, the combination with telephone-lines, of a plurality of connecting-cords with connecting-plugs attached thereto and adapted to be used to establish connections with the lines for conversation, seat-switches for said plugs, a supervisory relay for each cord, testing-circuits for said cords completed over a strand of eachand a common conductor, the individual portions of said. circuits including the contacts of the associated plug-seat and supervisory relays, substantially as described.

3. In a telephone system, the combinatio with telephone-lines, of a plurality of connecting cords and. plugs to establish connections with the lines for conversation, plugseat switches for said plugs, a testing device common to said cords, the testing-circuits of said cords comprising a strand of each and said common testing device, a supervisory relay for each cord, and means for connecting said device with the respective cords through the .medium of the associated supervisory relay and plug-seat switch, substantially as described.

4. In a telephone system, the combination with a plurality of telephone-lines, of a plurality of connecting cords and plugs to establish connections with the lines for conversation, supervisory relays for said cords a central common source of current associated with saidcords andadapted to be included in the telephone-lines to furnish current for conversation, a test-relay forvthe cords, plug-seat switches forsaid-plugs, and means for connecting :said test-relay-with the cords through the medium-of said-plug-seat switches and for disconnecting said relay therefrom through said supervisory relays when a connection is: established with the line for-conversation, substantially as-:de scribed.

5. In a telephone system the combination with telephone-lines, of a pluralityuof connecting cords and plugs to establish connections with the lines for conversation, seatswit'ches for'said plugs, supervisory relays for said cords, a testing device'common to said cords, testing-circuitsincluding a strand of eachcordand the saidcommon device, said device being connected with the cord through the medium of contactsofsaidrelays and plug-seat. switches, the plug-seat switches serving normally to disconnect said test device and the relay serving to disconnect the same during conversation, substantially as described.

6; In a telephone testing system, the combination with telephone lines, of a plurality of cord-circuits to establish connections with high-resistance test-relay'common to a plu rality of said cord'-circuits,- and means for connecting said relay with the cord-circuits for itesting purposes by the removal of the plug fronrlts :normal position, substantially as described.

' Signed by me at Chicago, county-of Cook,

1 State of Illinois, this 12th-day of June, 1903.

WILLIAM R W. DEAN.

*Witnesses:

ROBERT LEWIS AMEs, I EVA A. GARLOOK. 

